A passive optical network (PON, Passive Optical Network) technology is a point-to-multipoint fiber access technology. With continuous development of technologies, an EPON (Ethernet Passive Optical Network, Ethernet passive optical network), a GPON (Gigabit passive Optical Network, gigabit passive optical network), an NG PON (next generation PON), and the like emerge. To ensure network reliability, a PON network needs to support fast switching. FIG. 1 shows a PON network architecture, which includes a first OLT 10 (Optical Line Terminal, optical line terminal), a second OLT 12, an ODN (Optical Distribution Network, optical distribution network), and ONUs (Optical Network Unit, optical network unit). When the first OLT 10 serves as an active OLT, a feeder fiber between an active port on the first OLT 10 and the ODN is an active feeder fiber, and a feeder fiber between a standby port on the second OLT 12 and the ODN is a standby feeder fiber. In a case in which the active feeder fiber or the active port is faulty, switching to the standby port needs to be performed to recover a service and implement protection for the feeder fiber.
In order to further extend application of the PON, a time wavelength division multiplexing-passive optical network (Time wavelength division multiplexing-Passive Optical Network, TWDM-PON) is put forward in the industry. The TWDM-PON is a passive optical network that combines both WDM and TDM technologies, and includes an office-side OLT (optical line terminal), a user-side ONU (optical network unit) or ONT (optical network terminal), and an ODN (optical distribution network).
After initial access to a system, an existing ONU performs automatic calibration to implement alignment of all available receive and transmit wavelengths of the OLT. However, when new wavelength channels are required subsequently due to a gradual increase of users and a service scale, the new wavelength channels are not calibrated by the ONU, so that the ONU is unable to switch to a new wavelength channel to perform data communication, which further leads to inefficient use of the new wavelength channels and drastic waste of bandwidth.